1YF4:
reference: Trypsin inhibition by a peptide hormone: crystal structure of trypsin-vasopressin complex., Syed Ibrahim B, Pattabhi V, J Mol Biol 2005 May 20;348(5):1191-8. Epub 2005 Apr 1. PMID: 15854654

This OCA Structure page
uses Jmol, developed by the Jmol Development Team (documentation).